The functioning of many appliances such as washing machines, dryers and the like depends upon the voltage and frequency of the electrical power to which the appliance is connected. This dependency arises from the fact that the timing mechanism of the appliance is dependent on the frequency of the electrical power used to power the appliance. For example, the appliance will detect the frequency of the electrical power and use that frequency as a "clock" signal against which the sequencing and duration of various automatic operations will be set. Consequently, appliances which are made to operate on 60 Hz power will not function properly if the power is at a different frequency such as 50 Hz. Accordingly, it has heretofore been necessary to redesign the timing circuitry of the appliance if it is to be exported.
Where the only electrical conversion necessary is a voltage conversion such as on small appliances, it is common to simply install a transformer and switch in the appliance. A converter of this type is described in U.S. Pat. No. 3,833,821 to Weaver. However, such converters are only useful for such items as travel irons, hair dryers, hot hair combs, clothes steamers, coffee and tea brewers, contact lens or baby bottle sterilizers, electric razors and the like which do not have timing mechanisms which depend on the frequency of the power.
Since electrical appliances requiring clocks or timing mechanisms, such as cooking stoves with clock timers, washing machines, electrical dryers or the like, designed to operate on 110 volt, 60 Hz power will not function properly where the power is at, e.g., 50 Hz, the manufacturers of those appliances must incur substantial expense to redesign the electronics of the appliance to operate on the voltage and frequency of each country into which the appliance is to be imported. Further, since the appliances are constructed differently, the manufacturer will typically have to set up different assembly and production lines for the manufacture of those appliances depending upon whether they are for domestic or foreign use.
A need thus exists for a converter which will accept electrical power of a particular voltage or frequency, whether regulated or not, and convert that power to the voltage and frequency on which an appliance was designed to operate. The converted power would then be simply interconnected to the timing circuitry of the appliance. Such a device would eliminate the present requirement for redesigning the electronics of the appliance and would make any appliance presently designed to operate on the power available in one country operable on the power of any other country without the expense of separate assembly lines or electronic designs.